The present invention relates generally to internal combustion engines, and more particularly, to internal combustion engines having variable displacement.
Automotive vehicle designers and manufacturers are constantly searching for ways to met or exceed the increasingly difficult EPA standards on fuel efficiency and exhaust emissions. One method that has been realized for years is the possibility of obtaining increased fuel efficiency and less emissions by operating an engine on less than its full complement of cylinders during certain operating conditions. Accordingly, during part-load operation, it is possible to save fuel by operating, for example, an eight cylinder engine on only four cylinders, or a six cylinder engine on only three cylinders. These engines are commonly referred to as variable displacement internal combustion engines.
One type of variable displacement engine known in the art is commonly referred to as the 4-6-8 variable displacement engine, and was sold by the Cadillac division of General Motors Corporation in the early 1980""s. The 4-6-8 variable displacement engine utilizes a valve disabler system to disable the intake and exhaust valves of the inactive cylinders at part-load operation. This was typically accomplished by mechanically restricting the intake and exhaust valves of each inactive cylinder from opening. By disabling the valves, the valves remained in the closed position, thereby eliminating pumping losses.
While variable displacement engines have proven to significantly increase fuel economy and, consequently to reduce fuel emissions, variable displacement engines of the prior art have several deficiencies. First, the reciprocating pistons within the inactive cylinders generate friction as the pistons are continuously reciprocated during operation. Accordingly, the active cylinders must overcome the friction in the inactive cylinders, causing a reduction in the total power generated by the engine. In tests done on the 4-6-8 variable displacement engine, the engine only achieves approximately a fifteen percent (15%) increase in fuel efficiency when operating on only half of its cylinders due in part to the effects of friction between the pistons and the cylinder walls.
Additionally, when a cylinder has ceased operation for a considerable period of time, the temperature of the cylinder wall and other surfaces within the cylinder drop as compared to the continuously operating, fuel burning cylinders. The cooler, inoperative cylinders are required under various power needs to suddenly resume operation when power demand increases. This can cause combustion inefficiency compared with the continuously operated, warmer cylinders and brings about a lower average fuel burning efficiency and an increase in fuel consumption. Consequently, this results in higher pollution exhaust gases from the colder operating cylinders.
Therefore, there is a present need for a variable displacement engine which overcomes the deficiencies in the prior art.
The present invention provides a variable displacement internal combustion engine that addresses the deficiencies of the prior art. In accordance with aspects of the present invention, an internal combustion engine is provided. The engine includes a crankshaft, and a first cylinder that includes a first piston reciprocally movable within the cylinder to form a first working chamber. The first piston is operably connected to the crankshaft. The first cylinder also includes at least one intake port adapted to be connected in fluid communication with a source of air, and at least one exhaust port adapted to be connected to an exhaust manifold. The engine also includes a second cylinder that includes a second piston reciprocally movable within the second cylinder to form a second working chamber. The second piston is operably connected to the crankshaft. The second cylinder also includes at least one intake port and at least one exhaust port. The engine further includes a turbocharger operable for receiving exhaust gas from the first cylinder and operable for supplying compressed air to the second cylinder.
In one embodiment, the engine further includes means for controllably supplying fuel to the first and second working chambers, the means includes an engine control unit in communication with at least one sensor, and a fuel injection system in communication with the engine control unit. The fuel injection system is operable to deliver fuel to the second working chamber when the engine is operating in a part-load condition.
In accordance with another aspect of the present invention, an internal combustion engine having part-load and full-load operation is provided. The engine includes a first cylinder group which continuously operates during part-load and full-load operation, and a second cylinder group which operates during full-load operation but does not operate during part-load operation. The engine further includes a turbocharger having an inlet for receiving exhaust gas and an outlet for supplying compressed air. The turbocharger is operably arranged such that the inlet receives exhaust gas from the first cylinder group, and the outlet supplies compress air to the second cylinder group.
In accordance with yet another aspect of the present invention, an internal combustion engine is provided of the type having a first cylinder group, a second cylinder group, and means for controlling the operation of the first cylinder group and the second cylinder group such that the operation of the first and second cylinder groups are activated during full-load operation and the operation of the second cylinder group is deactivated during part-load operation. The improvement to the engine includes a turbocharger having an inlet for receiving exhaust gas and an outlet for supplying compressed air. The turbocharger is operably arranged such that the inlet receives exhaust gas from the first cylinder group, and the outlet supplies compress air to the second cylinder group.
In accordance with still another aspect of the present invention, a rotary engine is provided. The rotary engine includes an output shaft, and a first rotary unit that includes a first rotary housing defining a first cavity. A first rotor of substantial triangular shape is rotatably movable within the first rotary housing defining three working chambers. The rotor is operable to rotate with the output shaft. The rotary engine also includes a second rotary unit that includes a second rotary housing defining a second cavity. A second rotor of substantial triangular shape rotatably is movable within the first rotary housing defining three working chambers. The rotor is operable to rotate with the output shaft. The rotary engine further includes a turbocharger operable for receiving exhaust gas from the first rotary unit and operable for supplying compressed air to the second rotary unit.
In accordance with still yet another aspect of the present invention, an internal combustion engine is provided. The engine includes a first chamber operable for combustion, and a first piston movable within the first chamber. The engine also includes a second chamber operable for combustion, and a second piston movable within the second chamber. The engine further includes a turbocharger operable for receiving exhaust gas, and operable for supplying compressed air. The turbocharger is operably arranged such that the turbocharger receives exhaust gas from the first chamber, and supplies compress air to the second chamber.
In accordance with still another aspect of the present invention, an internal combustion engine is provided. The engine includes at least one first chamber operable for combustion and having at least one intake port and at least one exhaust port. A first piston is movable within the first chamber. The engine also includes at least one second chamber operable for combustion and having at least one intake port and at least one exhaust port. A second piston is movable with the second chamber. The engine also includes a turbocharger operable for receiving exhaust gas, and operable for supplying compressed air. The turbocharger is operably arranged such that the turbocharger receives exhaust gas from the first chamber, and supplies compress air to the second chamber. The engine further includes a variable displacement control system for controlling the operation of the first and second working chambers. The system operable to operate the first and second working chambers during full-load operation, and operable to operate only the first working chambers during part-load operation.
In accordance with still yet another aspect of the present invention, an internal combustion engine is provided. The engine includes at least one first chamber having at least one intake port and at least one exhaust port, and a first piston movable with the first chamber. The engine also includes at least one second chamber having at least one intake port and at least one exhaust port, and a second piston movable with the second chamber. A turbocharger is provided that is operable for receiving exhaust gas from the first chamber and operable to supply compressed air to the second chamber. The engine further includes a variable displacement control system for controlling the operation of the first and second working chambers during predetermined operating conditions, the system including an engine control unit in communication with at least one sensor operable to output a signal corresponding to engine operating conditions; and a fuel injection system in communication with the engine control unit. The fuel injection system is operable to deliver fuel to the second working chamber based on the signal of the sensor.